* [david grant]
> BUT I am still left with the problem that caused it for me: how do I
> backup (clone?) a btrfs file system with snapshots to another btrfs
> partition (apart from using dd). I just hope I don't get scolded again
> and told I am not up to it.
I don't think you can conveniently clone the filesystem including the
snapshots to another computer or partition using traditional userspace
tools like tar or rsync, since they'd end up de-linking the reflink-ness
of the snapshots, so that all the snapshots end up taking the full
space.
However, I can think of one or two strategies that might help you
achieve something close to what you actually want:
1. If the snapshots are just for "online backup", you could backup only
what you consider the live subvol (or even better: a very recent
snapshot of it), and then make snapshots on the target filesystem after
each backup. While this isn't really a backup including the snapshots,
it might serve the purpose you want.
2. You could rsync the oldest snapshot, make a snapshot of it on the
target filesystem named the same as your second-oldest snapshot, rsync
(--inplace) the second-oldest snapshot into that newly created snapshot,
and repeat until you've done all the snapshots. My head is already
spinning, but it seems to me that it should be possible to automate this
in a not-too-ugly shell script that also handles updates in a sane way.
This falls to bits, however, if the various snapshots are regularly
written to, or if you can't be sure of their creation order. (for dated
backup snapshots, there shouldn't be a problem).
What would be really awesome is some sort of "btrfs-send" program that
handles all this the best way for you, but I don't think that exists
(yet). User friendly tools will undoubtedly appear as btrfs is more
used, but I guess it's still partly in the "roll your own" early adopter
stage. :)
Øystein
--
"Windows is too dangerous to be left to Windows admins."
-- James Riden in the monastery
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